Now in its fourth edition, Rant on the Court Martial and Service Law has been fully updated to reflect the introduction of the Armed Forces Act 2021. This includes amendments to the constitution of the Court Martial and qualified majority verdicts, the ability to appoint a Circuit Judge as Judge Advocate, the power to rectify mistakes in Summary Appeal Court and Service Civilian Court, and amendments to the process for service complaints appeals. The book also considers the introduction of deprivation orders and driving disqualification orders, as well as the power of British overseas territories to apply the Armed Forces Act 2006. The new edition includes a new chapter offering extensive coverage of the Armed Forces Act 2021. This is in addition to updates to existing chapters regarding the historical context of the service justice system through to the current day, the service environment and powers of service police, the Court Martial, sentencing, and the appeals process. This is an essential handbook for those practicing in the service justice system and for academics researching service law.